1. Field of the Invention
The present invention relates to a semiconductor device, particularly relates to a technique which is effectively applied to a semiconductor device having a nonvolatile memory element.
2. Background Art
As the semiconductor device, for example, a nonvolatile semiconductor-memory-device called flash memory is known. In a memory cell of the flash memory, one-transistor system comprising one nonvolatile element, or two-transistor system comprising one nonvolatile memory element and one selection MISFET (Metal Insulator Semiconductor Field Effect Transistor), which are connected in series, are known. In the nonvolatile memory element; a floating gate type in which data are stored in a floating gate electrode between a semiconductor substrate and a control gate electrode; a MNOS (Metal Nitride Oxide Semiconductor) type in which an ON (Oxide/Nitride) film is used for a gate insulating film (data-storage insulating film) between the semiconductor substrate and the gate electrode, and data are stored in the gate insulating film; and a MONOS (Metal Oxide Nitride Oxide Semiconductor) type in which an ONO (Oxide/Nitride/Oxide) film is used for the gate insulating film (data-storage insulating film) between the semiconductor substrate and the gate electrode, and data are stored in the gate insulating film are known.
JP-A-2002-164449 discloses a nonvolatile memory element having a multi-storage configuration in which a memory-gate electrode is disposed on a main surface of the semiconductor substrate via the data-storage insulating film, and switching gate electrodes are disposed on both sides of the memory-gate electrode.